不同水耕年限稻田土壤水分运动特征研究

利用田间染色示踪和室内样品分析相结合的方法,研究了江汉平原不同水耕年限稻田土壤水分运动特征及其影响因素,期望为制定合理的稻田水分管理措施提供科学依据。结果表明:新稻田(水耕17a)与老稻田(水耕大于100a)土壤理化性质差异显著,引发土壤剖面内不同水分运动特征。新稻田垂直渗漏较老稻田明显,表现为新稻田有更大的染色深度。老稻田染色区域主要集中在耕作层,染色面积为48.52%;犁底层和底土层染色面积较小,仅为3.17%和0.2%。除耕作层外,新稻田其他土层染色面积均大于老稻田,且优先流特征较老稻田明显。老稻田侧向水分运动较新稻田强烈,其侧流剖面的染色面积(15.35%)显著高于新稻田(8.45%),老稻田侧向水流主要发生在犁底层以上。为减少稻田水分渗漏损失,老稻田可以通过减少农田-田埂-沟渠过渡区侧渗实现,而新稻田可采取少量多次的灌溉原则。

CHARACTERISTICS OF SOIL WATER TRANSPORT IN DIFFERENT AGED PADDY FIELDS

Based on the field dye tracing experiment and laboratory analysis of soil samples,the characteristics of soil water transport in different aged paddy fields were revealed.This study is expected to provide scientific basis for the reasonable filed water management.The results showed that significant differences of physical and chemical soil properties between new paddy field (NF,aged 17 years) and old paddy field (OF,aged more than 100 years),which was expected to affect the soil water movement processes.Water percolation was more likely to occur in the NF,which was identified by the higher saturated hydraulic conductivity (Ks) in the NF (13.98～78.35 cm/d) than that in the OF (4.35～49.37 cm/d).Highest Ks was observed in the plow layer,followed by the subsoil layer,and lowest in the plough pan.More obvious vertical percolation was observed in the NF than that in the OF,characterized by the deeper stained depth.For the OF,highest stained area was observed in the plow layer (48.52％),followed by the subsoil layer (3.17％),and lowest in the plough pan (0.20％).Except for the plow layer,NF was characterized by higher stained area and more obvious preferential flow paths in other soil layers than the OF.Stronger lateral water flow was observed in the OF (15.35％) than that in the NF (8.45％),which was characterized by the more stained area in the OF than the NF,and mainly distributed in the plow layer.In order to reduce the water losses in the paddy field,more attention should focus on the lateral water lose in the inner field-bund-canal transition zone for the OF,and the irrigation strategies of more times with less single irrigation amount was suitable for the NF.